Chet

Chet is a Leviathan tasked with finding Sam and Dean Winchester. Taking on the form of a credit card fraud tracker, he is able to use the position in the company to pinpoint the Winchester brothers' location. Driving all the way out there, he finds a spot where Sam used his credit card, phones his bosses and awaits orders, munching in the meantime on a side order of shop owner and melted cheese.

He later ambushes the brothers, but fortunately a powerful witch that the brothers have semi-helped early casts a paralysis spell that enables them to take Chet to Bobby, to torture, find out information and to see if there's anything that hurts the creature.